scholarly journals The Pitting Susceptibility Investigation of Passive Films Formed on X70, X80, and X100 Pipeline Steels by Electrochemical Noise and Mott-Schottky Measurements

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yang Zhao ◽  
Ping Liang ◽  
Yanhua Shi ◽  
Yunxia Zhang ◽  
Tao Yang
Keyword(s):  
Distribution Function ◽  
Electrochemical Noise ◽  
Pipeline Steel ◽  
Stochastic Theory ◽  
Gumbel Distribution ◽  
Passive Films ◽  
Initiation Rate ◽  
Pipeline Steels ◽  
X100 Pipeline Steel ◽  
Pit Initiation

The pitting susceptibility of passive films formed on X70, X80, and X100 pipeline steels was investigated by means of electrochemical noise (EN) and Mott-Schottky measurements. The EN results were analyzed according to the shot-noise theory and stochastic theory. Pit initiation process was analyzed quantitatively using the Weibull distribution function. Pit growth process was simulated by Gumbel distribution function. The experimental results of Mott-Schottky plots showed that the passive films formed on the three pipeline steels displayed an n-type semiconductor character, and the passive film for X100 pipeline steel has the lowest donor density (ND) among the three passive films. The EN results demonstrated that X100 pipeline steel had the lowest pit initiation rate and pit growth probability, which implied that the X100 pipeline steel had the lowest pitting susceptibility.

Study of EMISE Ionic Liquids Inhibitor on the Corrosion Behavior of Steel Rebar by Statistical Methods in Alkaline Chloride Solution

2014 ◽  
Vol 941-944 ◽  
pp. 1362-1366
Author(s):  
Xin Zhou ◽  
Guoxi Wu ◽  
Ren Chen
Keyword(s):  
Distribution Function ◽  
Ionic Liquids ◽  
Corrosion Behavior ◽  
Chloride Solution ◽  
Electrochemical Noise ◽  
Stochastic Theory ◽  
Gumbel Distribution ◽  
Inhibition Effect ◽  
Steel Rebar ◽  
Corrosion Pitting

The pit corrosion behavior of steel rebar in alkaline chloride solutions without and with EMISE ionic liquids inhibitor were investigated by means of electrochemical noise (EN). The experimental results of electrochemical noise measurement revealed that the pit corrosion was inhibited and corrosion pitting process was retarded significantly. The mechanism of the inhibition effect of the inhibitor was analyzed based upon the combined stochastic theory and shot noise theory using the Weibull distribution and Gumbel distribution function.

Microstructure and Mechanical Properties of Twinning M/A Islands in a X100 High Strength Pipeline Steel

2017 ◽  
Vol 896 ◽  
pp. 182-189 ◽  
Author(s):  
Ji Ming Zhang ◽  
Qiang Chi ◽  
Ling Kang Ji ◽  
Hui Feng ◽  
Yan Hua Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
High Strength ◽  
Pipeline Steels ◽  
Transmission Electron ◽  
Fine Microstructure ◽  
X100 Pipeline Steel ◽  
Deformation Hardening

Fine microstructure of twinning Martensite/austenite (M/A) islands in a X100 high strength pipeline steel were analyzed by the scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM), and a uniaxial compressive experiment of micro-pillar for a twinning M/A island was conducted in present paper. The experimental results showed that M/A islands in X100 pipeline steels were consisted of retained austenite and nanoscale twins with sizes of less than ten nanometers. There were a few small blocks of nanoscale twins in an M/A island. Volume fraction of twinning M/A islands had an important effect on mechanical properties of X100 pipeline steels, with the increase of twinning M/A islands fraction, yield strength of X100 pipeline steel increased, and impact toughness of X100 pipeline steel decreased. The micro-pillar compression showed that the nanoscale twinning M/A island exhibited the higher deformation hardening during the compressive test, and its uniaxial compressive strength could up to 1.35GPa ultrahigh stress level.

Bicarbonate, Temperature, and pH Influences on the Passivation of API-X100 Pipeline Steel in Simulated Groundwater Solutions

2014 ◽  
Author(s):  
Ibrahim M. Gadala ◽  
Akram Alfantazi
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Passive Film ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Environmental Parameters ◽  
Passive Films ◽  
Good Correspondence ◽  
Protective Properties ◽  
X100 Pipeline Steel

The influence of bicarbonate ion (HCO3−) concentration and related environmental parameters such as pH and temperature on the passivation of API-X100 pipeline steel is the focus of this investigation. NS4 solution simulating groundwater trapped under disbonded coatings at regions where near-neutral stress corrosion cracking (SCC) occurs was used as a reference. Bicarbonate content in the solutions was increased steadily and the critical HCO3− concentration at which passivation becomes evident is found using potentiodynamic polarization sweeps. Multi-step dissolution is observed especially in higher pH solutions, owing to the involvement of hydroxide ions (OH−) in the adsorption of hydrous Fe(OH)2. Dynamic electrochemical impedance spectroscopy (DEIS) is used to study and compare interfacial processes in active, pre-passive, passive, and trans-passive regions. The results of the potentiodynamic and DEIS tests achieve good agreement. The protective properties of the passive film formed at three different HCO3− concentrations (critical passivation and two higher concentrations) and temperatures (25, 50, and 75 °C) are studied. The combined effect of HCO3− and temperature resulted in a pH range from ∼6.7 to 9.3 for the nine conditions in the corresponding test matrix. Passive films were formed at a suitable anodic potential and then studied with electrochemical impedance spectroscopy (EIS), Mott-Schottky, and cyclic voltammetry (CV) tests. Evidence of adsorption and diffusion, in addition to significant resistance from the passive film, is observed and accounted for in the equivalent circuit, which achieved good correspondence when fitted with the experimental data. The protective properties of the overall passive film are enhanced with increased bicarbonate and decreased temperature. Positive slopes in the Mott-Schottky plots reveal the n-type semi-conductive behavior of the passive films in all conditions and the CV results highlight the proposed reaction sequences occurring in different potential scan regions. CV measurements also confirm the enhanced protective properties of passive films with increased bicarbonate and lower temperatures observed in the EIS analysis.

Effects of Finish Cooling Temperature on Microstructure and Properties of X100 Pipeline Steels

2016 ◽  
Vol 850 ◽  
pp. 993-999
Author(s):  
Shu Jun Jia ◽  
Qing You Liu ◽  
Ba Li ◽  
Hong Mei Hao
Keyword(s):  
Volume Fraction ◽  
Pipeline Steel ◽  
Steel Production ◽  
Mechanical Tests ◽  
Yield Ratio ◽  
Pipeline Steels ◽  
Cooling Temperature ◽  
Key Factor ◽  
X100 Pipeline Steel ◽  
Peak Value

The effect of finish cooling temperature on microstructure and mechanical properties of X100 pipeline steels were investigated through SEM, TEM and mechanical tests. The results showed that the effect of finish cooling temperature on tensile strength of studied steels were slight in the temperature range of 180°C~500°C. The yield ratio, yield strength and impact toughness all presented peak value when the finish cooling temperature was 360°C, however, both the volume fraction and particle size of MA component at 360°C finish cooling temperature had the minimum values. As a brittle hardening phase in bainite the increased number and enlarged size of the MA component were the key factor of the decrease of the yield ratio and toughness. Therefore, rational choosing finish cooling temperature could optimize the morphology and distribution of MA component to make sure the required strength and toughness for the X100 pipeline steel production.

scholarly journals Simple method for estimating daily and  total COVID-19 deaths using a Gumbel model

2020 ◽  
Author(s):  
Hiroshi Furutani ◽  
Tomoyuki Hiroyasu ◽  
Yoshiyasu Okuhara
Keyword(s):  
New York ◽  
New York City ◽  
Distribution Function ◽  
United Kingdom ◽  
York City ◽  
Gumbel Distribution ◽  
Series Data ◽  
Simple Method ◽  
The United Kingdom ◽  
Gumbel Model

Abstract The purpose of the present paper is to introduce a method for forecasting daily and total numbers of COVID-19-associated deaths. We apply the Gumbel distribution function for the analysis of time series data of the first wave. The Gumbel distribution function F(t) has a notable property of F(t) = 1/2.718 at the node (peak) point of the distribution. Therefore, we can forecast the number of total deaths N. In the present study, the Gumbel model gives the estimate N ≈ 2.718N1, where N1 is the partial sum of the daily numbers of deaths until the day of the peak. The proposed model can also forecast the daily numbers after the peak. We investigated the data of New York City, Belgium, Switzerland, Sweden, and the United Kingdom. The Gumbel model gives reasonable results for New York City, Belgium, and Switzerland. On the other hand, the proposed method underestimates N for Sweden and the United Kingdom. The proposed approach is very simple, and carrying out the analysis is easy. This method uses spreadsheet software for most of the calculations, and no special program is needed.

scholarly journals Effect of secondary peak temperature on microstructure and toughness in ICCGHAZ of laser-arc hybrid welded X100 pipeline steel joints

2020 ◽  
Vol 9 (4) ◽  
pp. 7838-7849
Author(s):  
Xiaonan Qi ◽  
Hongshuang Di ◽  
Xiaonan Wang ◽  
Zhenguang Liu ◽  
R.D.K Misra ◽  
...  
Keyword(s):  
Pipeline Steel ◽  
Peak Temperature ◽  
Secondary Peak ◽  
X100 Pipeline Steel ◽  
Steel Joints
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